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May 5th, 2011

CARO: Half of all computers running vulnerable versions of Adobe PDF Reader

Half of all avast! users are running an older versions of Adobe Reader on their computers that are vulnerable to a variety of malware attacks.

The avast! Virus Lab found that 49.41% of avast users were using the older Adobe Reader versions as of end-April. The number was also surprisingly stable, dropping by around five percentage points from the early March level of 55.71%.

“The numbers were a surprise to us,” said Jiri Sejtko, head virus analyst. “Because the avast! user pool is so large, this is a statistically significant indication of how vulnerable all computers are around the world.” The Virus Lab obtained the data on Adobe Readers from a global survey of users in the avast! CommunityIQ sensor system.

The older versions of Adobe are vulnerable to a variety of infected PDF files. Detecting these files was the theme of the Virus Lab’s “Grabbing the PDF by the tail” presentation at the CARO 2011 Workshop in Prague.

The technical presentation primarily looked the difference between structural heuristics and JavaScript heuristics. Structural heuristics work on a limited subset of files and are focused on PDF format and some file abnormalities. JavaScript heuristics rules have a wider, almost complete coverage.

“PDFs are an ideal channel for spreading malware,” said Jindrich Kubec, head of the avast! Virus Lab. “The bad guys don’t sleep, so combining detection techniques is really the way to go for anitivirus programs. For users, they need to make sure that their PDF reader is fully updated.”


  • Lynn Mayne

    I am one of them, i keep getting updates, but i had so much trouble loading the last one, i have been putting it off… think its time to update thanks for the warning…

  • David Oshel

    Something the article didn’t touch on, just what version is considered old? Is it anything older than v8? v9? v10? I wasn’t crazy about the user interface in v10 so I’m running v9…am I at risk??

  • Jason Mashak

    @David Oshel
    Visit and it should show you which is the current version to be using.

  • Abdulah

    I don’t use Adobe reader @ all :) , foxit Reader is much more simple and has all the features that I need. On top of that, I use chrome’s PDF reader which also runs in the sandbox which means, I’m good to go :)…

  • Jan Sirmer

    Chrom has a great “feature” when somebody is trying open PDF and chrom is not able to do it it will offer you open that PDF in adobe:)

  • Rednose

    As I use AIS, I have Adobe Reader sandboxed ;)

    Greetz, Red.

  • http://windowxp jhess

    i need avast!

  • James M Singleton

    Why is anyone still using Adobe Reader for Windows? If you must use it, keep it up to date to avoid problems.
    James M Singleton

  • Abdul Ellahib

    I don’t use Adobe PDF Reader, I noticed their software is vulnerable to many things, I enjoy Nitro PDF Much more.

    Plus you can get plug-ins on Mozilla Firefox to view PDF Files Online!

  • Irfan Nurhadi Satria

    Ah, I use SumatraPDF myself. Not only it’s completely free (and open source :), it is fast, and have Firefox/Chrome/Opera plug-in too.. Shame the feature list is not that good, but since I’m a home user, it’s fine by me.

  • Fernando Gregoire

    I keep the programs up to date when possible. Sometimes I need to use old versions because accessibility challenges.

  • HackToHell

    I prefer foxit reader , smaller , faster and less exploits(i remember two !)

  • shre54321

    thanks for protecting us avast!i luv avast!!!!